1. Field of the Invention
The present invention relates to an image forming apparatus such as a copying machine, a printer, a facsimile machine or a combination thereof, and so forth, which forms/records an image on a recording member such as a sheet of paper or a card.
2. Description of Related Art
Generally, a conventional image forming apparatus includes a single structure for supporting every main part of the image forming apparatus. In general, such conventional structures can be classified into two categories. One employs a pair of metal side plates facing each other, as disclosed in Japanese Laid-Open Patent Publication Nos. 6-317953 and 8-101546; the other employs a metal frame in which steel members are put together, as disclosed in Japanese Laid-Open Patent Publication No. 6-175419.
The structure which employs the pair of metal side plates has advantages in achieving low-costs, high transportation efficiency of elements, and high accuracy. However, it has shortcomings in heavy weight. Further, its production efficiency is low because the structure designed for one apparatus cannot be generally used for the other kinds of apparatuses.
The structure which employs the metal frame is light in weight and has high rigidity. Because it can be used for different kinds of image forming apparatuses, it provides advantages in achieving high productivity. However, this structure is disadvantageous in costs, transportation efficiency, and accuracy. Further, it requires welding facilities for producing the metal frame.
In the meanwhile, with the recent spread of digital technologies, in particular with the remarkable expansion of personal computers, printers are considerably more common. Further, a copying machine, a printer, and a facsimile machine, which have been produced independently, are now produced with a design by which common parts can be used in producing a variety of product-lines including copying machines, printers, facsimile machines, and so forth.